This disclosure generally relates to systems and methods for controlling the location of an end effector of a robot relative to a target object during the performance of automated procedures such as non-destructive inspection (NDI) and other maintenance operations.
Existing robot programming techniques require each individual robot motion sequence to be entered into a motion control process (e.g., motion script), typically involving on-line teaching or off-line programming methods—but these usually require a high level of expertise and effort from the robot programmers.
Standard open-loop programming techniques also have problems if the alignment between the robot and the target object deteriorates, which can be the case with ground-based robots that move over surfaces that may be uneven, have cracks, holes, or other discontinuities. Existing open-loop robot programming techniques cannot adapt to misalignment (for example, dead reckoning odometry alone is not sufficient since error builds up over time). To address this situation, some approaches use external hardware to provide continuous closed-loop feedback of the location of the scanner. An example of this is motion capture (see, e.g., U.S. Pat. Nos. 7,643,893 and 8,892,252), which use multiple cameras to track retro-reflective optical targets attached to the moving and target objects. Those types of solutions require that external hardware be set up prior to use, which can be problematic in some use cases. Other solutions use contact alignment processes to assist in aligning the end effector to a workpiece.